This invention relates to a continuous process for producing quick cooking (instant) rice which requires only about five minuts for swelling in hot, not necessarily boiling, water to be suitable for consumption, while retaining most of the nutritional value in the rice.
Standard milled white rice requires about 20 to 35 minutes of cooking in boiling water. In addition to the long cooking time required for the rice, the starch is sometimes not entirely gelatinized, or an undue number of the starch cells in the rice may burst to form a viscous, sticky, pasty cooked rice. For these reasons and others, the consumption of rice has been restricted for many years. Accordingly, considerable effort has been directed towards the production of quick cooking rice. Generally, quick cooking rice is rice that has been hydrated and/or gelatinized to various degrees and dried in such a manner to produce individual kernels.
An excellent discussion of quick cooking rice is given in RICE CHEMISTRY AND TECHNOLOGY edited by D. F. Houston, published by the American Association of Cereal Chemists, Incorporated, St. Paul, Minn., Chapter 15, Quick Cooking Rice, Robert L. Roberts, pages 381-399, the entire contents of which are incorporated by reference herein.
Generally most prior art methods of making quick cooking rice involve soaking the rice in water. For example, see U.S. Pat. Nos. 2,438,939; 2,733,147; 2,740,719; and 2,828,209. The soaking technique, however, is time consuming, involves a loss of valuable rice starch and produces a waste water pollution problem. Soaking involves the use of excess water which invariably leads to a dissolving of rice starch into the water which not only lowers the nutritional value of the rice (loss of carbohydrates and calories), but also results in the production of a starchy water effluent which must be disposed.
Another technique used in producing quick cooking rice is to fissure the rice and such method is disclosed in various patents including U.S. Pat. Nos. 3,157,514 and Norwegian Pat. No. 107,170. U.S. Pat. No. 3,157,514 suffers from the fact that it specifically requires hydrated rice to be used as a raw starting material. Further, U.S. Pat. No. 3,157,514 involves the soaking technique and cooling the rice before drying (a very energy wasteful step). The rice product of U.S. Pat. No. 3,157,514 is not completely gelatinized and thus requires boiling to render the rice suitable for consumption. The rice produced by the method of Norwegian Pat. No. 107,170 is also not completely gelatinized and thus requires boiling in water before consumption.
Still another process to produce quick cooking rice is given in U.S. Pat. No. 2,937,946 which discloses the use of spraying with hot water to gelatinize the rice. This technique requires large amounts of hot water and is thus very energy consuming. Also, the process of U.S. Pat. No. 2,937,946 involves a great deal of time to achieve gelatinization.